EE342.01: MATLAB M-FILE FOR COMPARING DISCRETE-TIME SIGNAL MAGNITUDE SPECTRA

%
% Filename: example10.m
%
% Description: m-file to plot spectra of xslow[n]=(.95^n)u[n]
%              and xfast[n]=(-.95^n)u[n].
%

n = 0:20;                       % define n, xslow[n], xfast[n]
xslow = 0.95.^n;
xfast = (-0.95).^n;

subplot(2,2,1);                 % plot xslow[n]
stem(n,xslow,'filled');
xlabel('n'); ylabel('xslow[n]');
title('DT Signal xslow[n] = (0.95^n)u[n]');

subplot(2,2,3);                 % plot xfast[n]
stem(n,xfast,'filled');
xlabel('n'); ylabel('x[n]');
title('DT Signal xfast[n] = (-0.95^n)u[n]');

W = -3*pi:0.01:3*pi;            % define W, Xslow(W), Xfast(W)
Xslow = 1./(1 - 0.95*exp(-j*W));
Xfast = 1./(1 + 0.95*exp(-j*W));

subplot(2,2,2);                 % plot |Xslow(W)|
plot(W,abs(Xslow));
xlabel('W '); ylabel('|Xslow(W)|');
title('Magnitude (Amplitude) Spectra of xslow[n]');

subplot(2,2,4);                 % plot |Xfast(W)|
plot(W,abs(Xfast));
xlabel('W '); ylabel('|Xfast(W)|');
title('Magnitude (Amplitude) Spectra of xfast[n]');